fix an IPSCCP bug I introduced when I changed IPSCCP to start working on

functions that don't have local linkage.  Basically, we need to be more
careful about propagating argument information to functions whose results
we aren't tracking.  This fixes a miscompilation of 
LLVMCConfigurationEmitter.cpp when built with an llvm-gcc that has ipsccp
enabled.

llvm-svn: 85923